This is usually considered to be the simplified form. The numerator zeros are irrational, so the numerator has no integer factors. The denominator zeros are x=-8, 10, but "simplified" usually means "multiplied out, rather than factored."
If you wanted to, you could write the expression as
.. 1 - (34/9)/(x -10) -(128/9)/(x +8)
This is more suitable for finding asymptotes and for doing integration, but may not be considered "simplified."